1. Technical Field
The present invention generally relates to processors and in particular to dynamic voltage and frequency scaling within a microprocessor.
2. Description of the Related Art
Multiple high end system architectures supply redundant power sources to one or more processors. The system architecture comprises a current-sharing power supply such as a Direct Current Assembly (DCA), whereby the DCA positions a microcontroller in between the processors and voltage regulator modules (VRMs). When a voltage change request is made by the processor to the DCA, errors in the request transmission can occur. The errors include, but are not limited to, failed delivery of the voltage change request due to noise in the communication channel, failure in the VRM, and/or failed delivery of the response affirming whether the voltage change request succeeded or failed.
Several suggested solutions exist which allow the voltage change request within the high end system architecture to be processed and confirmed. A first suggested solution includes issuing a “poll” command by the processor, following each voltage command, to determine status of a voltage change request. Issuing a polling command utilizes additional bandwidth between the processor and the DCA, and thereby consuming bandwidth designated to other operations. Consuming additional processor bandwidth utilizes bandwidth needed for system power management sensors, and therefore adversely affecting the quality of power management within the system architecture. A second suggested solution includes transmitting a “complete voltage transition” signal from the DCA to the processor. Transmitting the “complete voltage transition” signal requires additional input/output pins for each voltage domain and the pins are shared to provide a scalable solution for the high end system architecture. However, when the one or more input/output pins are shared, the processor has difficulty determining which of the DCAs sent the “complete voltage transition” signal. Therefore the voltage change request is not completed. The suggested solutions are neither optimal nor preferred solutions.